Here in California the basic law is you can't make any modification to anything. I am not joking, if you were to dissect the California Vehicle code book what it basically comes down to is most any modification is illegal if the cop wants to take the time to ticket you.

A turn signal lens on a 2003 Blazer are amber.

The AM ones which are clear are illegal, it doesn't matter that you can put an amber bulb in it, it is illegal.

This Lexus with clear lenses is legal, because it came from the factory that way.

I don't know the legality of the HID light conversions but I have to believe they are illegal.

I understand that may not make sense, I an talking about the law and nothing else.